Slack adjuster



Jan. 21, 1958 M. K. cOslgUN" 2,820,532

SLACK ADJUSTER 2 Sheets-Sheet 1 mi Q, Kaff@ o. (bl.

Jan. 21, 1958 M. cosKuN SLACK ADJUSTER 2 Sheets-Sheet 2 Filed Aug. 28,1953 INVENTR. ASLZL snackv Anrosrnn Mehmet K. Coskun, Granite City,lll., assignor to American Steel Foundries, Chicago, Ill., a corporationof New Jersey Application August v28, 1953,Serial No. 377,151` 8 Claims.(Cl. 18S-196) The invention relates tor'slackradjusters and particularlyto slack adjuste-rsrthat may be'incorporated in the brake actuatinglinkage of railway equipment.

It is a principal object of the invention toprovide novel automaticslack adjusters for use with the brake actuating linkage of a railedvehicle.

I-t is a specific object of the invention to provide a novelratchet-pawl arrangement in combination with pawl control linkage toafford the desiredrlautomatic adjustment of the mentioned brake linkagein response to wear on the friction surface of a brake mechanism.

lt is another specific Object of the invention to pro'- vide a novelratchet-pawl arrangement in a linkage of the type. described incombination with a dilerential gear mechanism whereby the mentionedautomatici adjustment is attorded.

These and other objects of the invention will become apparent in thecourse of the following description and from an examination of theconcerned drawings, wherein:

Figure 1 is a fragmentary elevational view of the operative parts of oneembodiment of the invention;

Figure 2 is a sectional view taken along line 2--2 of Figure l;

Figure 2a is a fragmentary view taken on line 2a-2a of Figure 2;

Figure 3 is a fragment-ary side elevational View, similar to Figure l,of another embodiment of the invention;

Figure 4 is a sectional view takenalong line 4-4 of Figure 3, and

Figure 5 is another View similar to Figure l of another embodiment ofthe invention.

Describing the invention in detail and considering Figure 1, the numeral2 indicates a pull rod, the left end of which is connected -to a brakingmechanism (not shown) as is well understood by those skilled in the art.The pull rod 2 has formed thereon a ratchet or series of gear teeth 4,said teeth being formed on the end of the pull rod that cooperates withthe slack adjust, ing mechanism hereinafter described. A positioninglink 6 is provided with one end pivotally fixed as at 8 to the vehicleframe indicated at 10. The opposite end of the positioning link 6 isprovided with an elongated slot 12. An actuating lever 14 is preferablypivoted to the frame as at 16 and extends downwardly toward the rod 2and link 6. The lower end of the lever 14, as seen in Figure 2, isbifurcated -as at 18, 18, said bifurcated portion receiving or embracingthe pull rod 2 and the positioning link 6. A roller 20 `is pivotallymounted by means of pin 22 to the lower or bifurcated end of theactuating lever 14.` The pin 22 in addition to carrying the roller 20also pivotally mounts an actuating link 24, said actuating link having acam 26 rigidly formed therewith. The cam 26 is generally oblong in shapehaving at the lower end thereof` a V-shaped opening 27 as seen mostclearly in Figure 2a. Figure 2a is similar to Figui-e1 but with members18- and-6 removed. The pin 22 is disposed in the slot 12formedY-atjtheendof thepositioning link 6. in such a manner as t-oprovide aglost motion rice connection between ltheactuating lever 14 andthe frame 10 via the positioning link 6. The lower end ofthe actuatinglink 24-is pivotally connected to the lower end of a'v connecting link28, said connecting link extending upwardly to make pin and slotconnection as at 30 with an extended portion of a pawl 32. The pawl 32vis pivotally connected by means of pin 34 to one side of the bifurcatedend portion of the actuating lever 14. The positioning link 6 isrprovided with a cam actuating lug 36 immediately below the elongatedslot12. The lug 36 serves to actuate the cam 26 during the actionhereinafter described. It should be noted that the actuating link 24,the connecting link 28 and the cam 26 together comprise a toggleindicated generally at 40, said toggle cooperatingV with the pawlv32during the action hereinafter described.

The operation of the arrangement of Figures l and 2 is `relativelysimple. Brake actuation is accomplished by counterclockwise movement ofthe actuating lever 14, said movement being carried to the pull rod 2via the pawl 32 which is engaged with one of the teeth of the ratchet 4.Brake actuating movement is, of course, to the right as seen in Figurel. Under normal operation the lever'14 carries the pin 22 and toggle 40horizontally in the slot 12 of the positioning link 6 to a position inthe slot short of the lug 36. As the friction surfaces begin to wear thetoggle 40 and pin 22 are carried further to the right of the slot 12until finally after a predetermined amount of wear the lug 36 strikesthe left side of the V-shaped opening of the cam 26 causing theactuating link 24 to pivot in a clockwise direction about the pin 22whereby the connecting link 28 is raised vertically. After the lug 36strikes the cam 26, the cam and the link 24 move to the right of the lug36. Maximum vertical movement of the connecting link 28 will cause thepin and slot connection 30, between the con'- necting link 28 and thepawl 32, to take up a position at the lower end of said slot. When thisoccurs the toggle 40 no longer exerts any pressure on the pawl 32 tomain# tain said pawl in engagement with a particular tooth of theratchet 4. Thus upon release of the brake, that is, clockwise movementof the actua-ting lever 14, pawl 32 will skip a certain number of teethon the ratchet 4 and take up a new position on the pull rod 2. When thenew position is reached the actuating lug strikes the right side of theV-shaped opening of the cam 26 as the cam 26 an the link 24 move fromthe right to the left of the lug 36, causing the actuating link 24 torotate in a counterclockwise direction which returns the connecting link28 to original position, that is, with the pin and slot connection 30disposed in the upper end of said slot. In this position the toggle 40maintains the pawl 32 in engagement with a particular tooth of theratchet 4. During both clockwise and counterclockwise movements of theactuating lever 14 the new position is maintained until wear in thebrake mechanism or slack in the linkage again causes the actuating lever14 to carry the pin 22 and toggle 40 an excessive distance in the slot12.

Directing attention now to Figures 3 and 4 wherein is illustrated asecond embodiment of the invention, it will be seen that in. thisembodiment a pull rod 44 isagain provided, said pull rod being connectedto a brake mechanism as is well understood by those skilled in the art.A series of ratchet or gear teeth 46 are formed on one side of the pullrod 44. A positioning link or pawl bar 48 is also provided, said pawlbar 48 being disposed adjacent pull rod 44 and preferably parallelthereto. One end of the bar 48 is provided with a conventional lostmotion connection 50 to the vehicle or vehicle frame 10. rlhe other endof the pawl bar 48 is provided with` a spring loaded pawl 52, said pawl52 beingdisposed to engage, the gear teeth 46 formed on the pull rod 44,

Intermediate the mentioned ends of the pawl bar 48 another series ofgear teeth 54 are formed on the bar on the side adjacent the gear teeth46 formed on the pull rod 44. An actuating lever S6 is again pivotally,attached as at 58 to the vehicle or vehicle frame 10. A differentialconnection indicated generally at 60 is provided between the actuatinglever 56, the pull rod 44v and the pawl bar 48. As best seen in Figure4, the differential connection comprises a lower bifurcated end of theactuating lever 56, said lower end pivotally mounting by means of pin 62a pinion gear 64. The pinion gear 64 is disposed intermediate guideplates 66, 66, said guide plates also being pivotally carried by the pin62. In vertical arrangement the pinion gear 64 is disposed intermediatethe pull rod 44 and the pawl bar 48 in such a manner that the piniongear 64 is engaged with the gear teeth 54 on the pawl bar and the gearteeth 46 on the pull rod. The guide plates 66, 66 extend vertically andembrace at opposite ends the pawl bar 48 and the pull rod 44. Rollers68, 68 are pivotally carried by opposite ends of the guide plates 66,66, each roller being disposed outboardly of the adjacent pull rod orpawl bar and engaged with a flat surface on the adjacent side of thepawl bar or pull rod. The rollers 68, 68 serve to maintain the pull rod44 and the pawl bar 48 in substantially parallel arrangement during theaction hereinafter described.

In normal operation of the embodiment of Figures 3 and 4, the pawl barand carried pawl 52 are maintained in relatively fixed position with thepull rod 44. The brake mechanism is actuated by moving the lever 56 in acounterclockwise direction. The counterclockwise movement of the lever56 carries the pinion gear 64 to the right which in turn carries thepull rod 44 and the pawl bar 48 to the right. Thus the pawl bar and pullrod move as a unit with the actuating lever 56 during normal operationof the brakes or until excessive brake Wear or other slack causes thelost motion connection to prevent further movement to the right of thepawl bar 48. When said excessive brake wear occurs the pawl bar 48 ishalted and continued movement of the actuating lever 56 causes the gear64 to roll on the gear teeth 54 and further drive the pull rod 44 to theright. As this action occurs, the spring loaded pawl 52 is urged to skipthe teeth 46 ou the pull rod 44 whereby the pull rod takes up a newposition relative to the pawl bar 48. Thus again the embodiment ofFigures 3 and 4 provides automatic take up of the slack in a brakelinkage due to excessive wear on the brake mechanism or in any part ofthe linkage.

The embodiment of Figure 5 is in principle similar are provided. Apositioning unit comprising a link 76 having one end pivotally fixed tothe frame itl and at the other end having a pin and slot or lost motionconnection 78 to a pawl bar 80 serves to cooperate with the pull rod 70so as to provide the desired automatic slack adjustment. The pawl bar isguidably and reciprocally mounted in a slot 82 formed on an arm S4- ofthe pull rod 70. The other end of the pawl bar 80 is provided with abifurcated section which carries a spring loaded pawl 86, said pawlbeing engageable with the ratchet teeth 72 of the pull rod 7d. Anactuating iever S8 is again pivotally connected to the frame or vehicleas at 90. The lower end of the actuating lever 8S pivotally carries apinion gear 92, said gear 92 being operatively connected to the gearteeth 74 formed on the pull rod 70 and to other gear teeth 94 formed onthe pawl bar 80.

In operation of the embodiment of Figure 5, the actuating lever 88 ismoved counterclockwise to energize the associated brake mechanism. Thecounterclockwise motion of the actuating lever 88 carries the pull rod70 and pawl bar 80 to the right as seen in the gure. When the operationis normal, the pull rod and pawl bar move as a unit. However, uponexcessive wear in the brake mechanism the link 76 takes up the slackoffered by the lost motion connection 78 and prevents the pawl bar 80from further movement to the right. This restriction of movement of thepawl bar 80 causes the pinion gear 92 to the roll on the gear teeth 94and drive the pull rod 70 further to the right, whereupon the springloaded pawl 86 takes up a new position on the ratchet 72 and the slackin the brake linkage is automatically absorbed.

I claim:

1. In an automatic slack adjuster, a pull rod having a ratchet formedthereon, a positioning link having one end thereof fixed to the vehicleframe, an actuating lever pivoted to the vehicle and having a bifurcatedend embracing the rod and link, a roller pivoted to the lever andsupporting the rod, a lost motion connection between the lever and thepositioning link, a pawl pivoted to the lever and engaging the ratchet,a toggle connected to the pawl and having an operative connection to thelink, said toggle vbeing operative to maintain the pawl and ratchet inengagement, and means associated with the link and toggle to trigger thepawl and accommodate movement of same on the ratchet after apredetermined movement of the lever relative to the link.

2. A slack adjuster according to claim l, wherein said toggle consistsof a connecting link having at one end a pin and slot connection to thepawl, an actuating link pivotally connected to the other end of theconnecting link, a cam on the actuating link and a lug on thepositioning link engageable with the cam.

3. In an automatic slack adjusting mechanism, a pull rod having aratchet formed thereon, a positioning link fixed to the vehicle frame atone end and having a slot at the other end, an actuating lever pivotedto the vehicle frame, a piu on the lever disposed in said slot, a pawlpivoted to the lever and engaged with the ratchet, means to lock thepawl in position on the ratchet during a normal operation within apredetermined range of movement of the lever, said means accommodatingmovement of the pawl on the ratchet in movement of the lever beyond saidpredetermined range.

4. An automatic slack adjusting mechanism according to claim 3, whereinsaid means comprises a cam pivoted on said pin, an actuating link xed tothe cam, a connecting link pivoted to the actuating link and having apin and slot connection to the pawl, and a lug on the positioning linkengageable with the cam to actuate same.

5. In an automatic slack adjuster for the brake actuating mechanism of arailed vehicle, a pull rod having an operative connection to a brakemechanism, ratchet teethformed on one end of the pull rod, a positioninglink having at one end thereof a connection with the vehicle and havingits other end adjacent said end of the pull rod, an actuating leverpivoted on the vehicle and positioned substantially normal to the pullrod, said actuating lever having a roller mounted thereon on an axisparallel with pivot axis of the actuating lever, said roller havingrolling engagement with the underside of the pull rod to support thesame, the actuating lever having means for supporting the positioninglink, and means operatively interconnecting the adjacent ends of thepull rod and positioning link including a pawl carried by the actuatinglever and engageable with said ratchet teeth for controlling themovement of the pull rod by the actuating lever, the positioning linkhaving lost motion between its connection with the pull rod and itsconnection with the vehicle.

6. In an automatic slack adjuster for a brake actuating mechanism of arailed vehicle, an actuating lever pivoted to the vehicle, a pull rodconnected to a brake mechanism, ratchet teeth formed on the pull rod, asingle pawl pivoted on the factuating Ilever and engageable with theratchet teeth, and means to change the position of the pawl on theratchet teeth and thereby adjust for wear on the brake mechanismincluding los't motion connection between the actuating lever and thevehicle operative at a predetermined portion of movement of theactuating lever for positively retaining the pawl in engagement with therachet teeth and releasing it therefrom, respectively, and rotativemeans for supporting the pull rod.

7. In an automatic slack adjusting device in a railed vehicle, a pullrod having ratchet teeth thereon, an actuating lever pivoted on thevehicle and having a swinging end disposed substantially normal to thepull rod, a roller carried by the lever adjacent the swinging endthereof and supporting the pull rod, a single pawl pivotally mounted onthe lever and engageable with any of said ratchet teeth, and means forvarying the relative positions of the pawl and ratchet teeth, said meansincluding a positioning link having a connection to the vehicle and tothe actuating lever, one of said connections being a pivotal connectionand the other of said connections being a lost motion connection.

8. In an automatic slack adjuster for a brake actuating mechanism of arailed vehicle; an actuating lever pivoted to the vehicle and having aroller pivotally carried adja cent the swinging end thereof; a pull rodsupported by said roller, said rod having at one end thereof anoperative connection to the brake mechanism and having ratchet teethformed therein adjacent the other end thereof, and a single pivotal pawlon the lever engageable with said teeth; a positioning link having atone end thereof a connection with the vehicle and having at the otherend thereof a connection with the lever, one of said connections of thepositioning link including a lost motion device, the connection betweenthe positioning link and lever including means supporting the adjacentend of the positioning link by the lever and linkage connected betweenthe positioning link and pawl for adjusting the position of the pawlrelative to the ratchet teeth in response to relative movement betweenthe lever and positioning link.

References Cited in the tile of this patent UNITED STATES PATENTS1,908,315 Bryant May 9, 1933 2,270,600 Ohlson Ian. 20, 1942 FOREIGNPATENTS 528,169 France Oct. l1, 1921 165,819 Great Britain July 11, 1921

